Many security systems include various types of sensors and monitors, such as those for detecting intrusion, presence of particles of combustion, motion within a given area, and so forth. The present invention is directed in general to such systems which include motion detectors, and more particularly to a test arrangement and method for insuring the operability of the motion detectors, and the system in which the motion detectors are connected, with a minimum of inconvenience and false alarming.
The type of test for a motion detector is frequently termed a "walk test". The unit generally includes a visible indicator, such as a light-emitting diode (led), or some similar unit which will provide a visible indication when energized. In its simplest arrangement, the one testing the unit merely walks in the protected zone, and visually inspects the state ("off" or "on") of the led to determine whether his movement has been detected. A bell or other audible output unit is generally connected to a controller which receives the alarm-indicating signals from the motion detector, and this bell sounds to confirm to the person doing the walk test that the controller "saw" his movement. If there are a plurality of motion detectors being supervised by a single controller, as is generally the case, the system does not know which motion detector was alarmed. Moreover the continual sounding of the audible output as the one testing goes from detector to detector develops the "cry wolf" syndrome, and generally the attention paid to the audible output diminishes with successive testing. There is also a certain interruption or annoyance caused by the sounding of the bell during the testing.
Of course the particular detector need not send an alarm signal back to the controller, but if there is no response from the system, the portion of the system network between this individual detector and the controller is not tested and confirmed as being in readiness to convey the signal if there were a real alarm.
Another type of walk test for such systems may include a mechanical switch, generally in the base or housing of the motion detector, which can be reached by the person doing the motion test. Very often when the motion detector is above a normal arm's reach, a pole or other extension member must be carried to actuate the switch and enable the led. This is awkward and suffers from the same drawbacks of the switch testing described above, in that the audible confirmation is annoying and diminishes the attention paid to the actual alarm signal. In some variations the switch is made to restore automatically after a predetermined time, to force the led back to the off state.
One attempt to improve upon the walk test arrangement of such motion detector systems includes the provision of a communication circuit coupled with the motion detector sensor, so that this circuit can send a signal back to the controller when the sensor detects motion in the protected zone. The controller recognizes the alarm-indicating signal from the communication circuit, and then sends a signal back to the communication circuit to energize the led or other output. This can be effected through a relay or semiconductor switch in the communication circuit. As soon as the motion ceases in this system, the relay switch is deenergized and the led is no longer illuminated. In this arrangement the next movement adjacent the sensor must again send a signal back to the controller, with a resulting command from the controller to again illuminate the led. This creates a system delay which slows down the effective testing of the motion detector arrangement.
It is therefore a principal consideration of the present invention to provide an improved walk test system for a security arrangement which overcomes the deficiencies of the earlier systems as set out above.
A more particular consideration of the present invention is the provision of such an improved system and testing arrangement in which, after the initial recognition at the controller of an alarm sensed back at the motion detector, the controller sends back a "turn-on" signal to enable the led. Thereafter the led follows the output of the local motion detector and is immediately illuminated when the next motion occurs, thus obviating the system delay encountered in earlier systems.
Another significant consideration of the present invention is the provision of such an improved testing arrangement connected in a hierarchical system, with a first order controller communicating through a second order controller to a plurality of transponders. The walk test can check not only the second order but also the first order controller, and associated components. This system can also examine different conditions, such as appropriate operation of smoke detectors and/or access control sensors, system batteries fully charged, lights off (at preassigned times), heat turned down, and so forth, before allowing the led to be energized to indicate those conditions have been satisfied.